1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel and fabricating method thereof, by which brightness thereof is enhanced.
2. Description of the Background Art
Generally, a plasma display panel (hereinafter abbreviated PDP), in which barrier ribs provided between front and rear glasses formed of soda-lime glass define one unit cell, is a device for implementing pictorial images. When inert gas such as He—Xe, He—Ne, or the like within each cell is discharged by RF voltage to generate vacuum ultraviolet rays, phosphor provided between the barrier ribs becomes luminous to implement the pictorial images or video. As the next generation display device, the PDP, which facilitates to enable its slim size and wide-screen and has such a feature as low power consumption and the like, is spotlighted.
PDP is classified into a DC type and an AC type according to an impressed drive voltage waveform and a discharge cell structure. The big difference between the AC and DC types lies in that external resistance for current restriction to prevent a discharge current from flowing during voltage impression should be provided to the DC type PDP having electrodes exposed to a discharge space. In case of the AC type PDP, a dielectric layer covers electrodes to naturally form capacitance enabling the current restriction and to protect the electrodes against ionic impact on discharge. Hence, endurance of the AC type PDP is superior to that of the DC type PDP. For such a reason, it is expected that PDP will adopt the AC drive type. And, the AC drive type PDP is driven in a manner of applying an AC voltage between electrodes having a dielectric inserted therein to trigger discharge each half cycle. Since the AC drive type PDP uses the dielectric, a surface of the dielectric is charged with electricity so that a memory effect can be brought about by a low impressed voltage using the electric charges. A configuration of the AC drive type PDP is shown in FIG. 1.
FIG. 1 is a perspective diagram of a PDP according to a related art. Referring to FIG. 1, a PDP 100 includes a front substrate 10 of an upper panel plate displaying images thereon and a rear substrate 20 of a lower panel plate forming a back face of the PDP 100. The front substrate 10 is assembled parallel to the rear substrate 20 to leave a prescribed distance from the rear substrate 20. Beneath the front substrate 10 of the upper panel plate, a sustain electrode 11 for sustaining light emission of a cell by mutual discharge in one pixel is provided. In doing so, a transparent electrode 11a formed of transparent ITO and a bus electrode 11b formed of a metal based material forms a pair to construct the sustain electrode 11. The sustain electrode 11 is covered with a dielectric layer 12 insulating electrode pairs from each other to restrict a discharge current. And, a protective layer 13 is formed by depositing MgO on the dielectric layer 12 to facilitate discharge conditions. A layout of the PDP upper plate is shown in FIG. 2.
On the rear substrate 20 of the lower panel plate, a plurality of stripe or well type barrier ribs 21 are arranged parallel to each other to define a plurality of discharge spaces, i.e., a plurality of cells. And, a plurality of address electrodes 22 for generating vacuum ultraviolet rays by performing address discharge in an intersection with the sustain electrode 11 each are arranged parallel to a plurality of the barrier ribs 21, respectively. An R/G/B phosphor layer 23 that emits visible rays for image display is coated on the rear substrate 20. A black matrix (not shown in the drawing), which is operative in cutting off light to reduce reflection by absorbing external light generated from outside the front substrate 10 and is also operative in enhancing color purity and contrast, is arranged on the barrier ribs 21. And, inert gas such as He+Ne, Ne+Xe, He+Xe+Ne, and the like is injected in the discharge spaces provided between the front substrate 10, the rear substrate 20, and the barrier ribs 21, respectively.
In the above-configured PDP, after the address discharge between the address electrode 22 of the rear substrate and the sustain electrode of the front substrate, continuous display discharge takes place for the selected cell. In doing so, vacuum ultraviolet rays generated from the discharge excite the phosphor to emit visible rays so that a specific image can be provided.
Specifically, in the AC drive type PDP, the image can be displayed by the sustain discharge following the confronting discharge. More specifically, in case that a voltage is applied to the address electrode 22 after voltage impression on the sustain electrode 11, the discharge, i.e., confronting discharge, occurs between the electrodes 22 and 11 to generate ultraviolet rays. And, the generated ultraviolet rays excite the phosphor 23 to emit the visible rays. Thereafter, as a sustain pulse is applied to the sustain electrode pair 11 to trigger the discharge, i.e., sustain discharge, the light emission of the confronting discharge is maintained to implement images.
FIG. 3 is a cross-sectional diagram of an upper plate according to a related art for explaining a discharge path. Referring to FIG. 3, a discharge path in maintaining the discharge by applying a voltage to the sustain electrode pair 11 on sustain discharge starts from an area (minimum discharge radius R) closest to the sustain electrode 11 and then extends to a distant area (maximum discharge radius R) according to an elapse of sustain discharge time. In doing so, as the area of the minimum discharge radius R has the maximum electric field strength, density of electrons and ions formed nearby becomes highest. Specifically, most of the electrons at high temperature (i.e., with high energy) exist in the area of the minimum discharge radius R. The high density of the electrons and ions increases the density of the ultraviolet rays exciting the phosphor 23, thereby increasing brightness. If the density of the electrons and ions is low, the density of the ultraviolet rays decreases to lower the brightness. Hence, in order to enhance the brightness, a level of the sustain voltage applied to the sustain electrode pair 11 is raised to increase the density of the electrons and ions generated from the sustain discharge.
However, since low voltage is applied to trigger the sustain discharge in the related art AC drive type PDP, it is unable to expect the brightness enhancement of the PDP according to the high voltage of the sustain discharge.